Auto merge of #500 - medium-endian:patch-1, r=emilio
Auto merge of #500 - medium-endian:patch-1, r=emilio

Clarify/correct command line usage

cargo installs bindgen to the local bin repo and not the current directory.

rust-lang/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,emilio/rust-bindgen,rust-lang/rust-bindgen,rust-lang/rust-bindgen,emilio/rust-bindgen,rust-lang/rust-bindgen,emilio/rust-bindgen